In conventional 3GPP LTE systems, downlink hybrid automatic repeat request (HARQ) feedback information for each downlink (DL) subframe is provided to an evolved Node B (eNB) in corresponding separate uplink (UL) subframes. For example, in frequency-division duplexing (FDD) wireless communications, a UE transmits separate UL subframes, each of which carry HARQ acknowledgement (ACK) or negative acknowledgement (NACK) feedback information for corresponding individual DL subframes. The separate UL subframes carrying the HARQ ACK or NACK feedback (collectively and alternatively referred to as HARQ ACK/NACK) are each offset from the corresponding DL subframes according to a predefined fixed relationship.
FIG. 1 illustrates an example timing diagram of the aforementioned HARQ feedback that is defined in 3GPP technical specification (TS) number 36.213 (3GPP TS 36.213). This definition has remained unchanged since LTE release version number eight (LTE Rel. 8). As shown in FIG. 1, if a UE receives a physical downlink shared channel (PDSCH) “a” in subframe index N, the UE then transmits HARQ ACK/NACK information bits for “a” in UL subframe index N+4. Similarly, HARQ ACK/NACK feedback for “b” in DL subframe index N+1 is transmitted by the UE in UL subframe index N+5, and so forth. Thus, if the UE receives PDSCH “a”-“l”, the UE sends HARQ ACK/NACK response in each of corresponding UL subframes indexes N+4 through N+15.